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Arnaldo Carvalho de Melo 0d3d237651 perf evlist: No need to setup affinities when disabling events for pid targets 
When the target is a pid, not started by 'perf stat' we need to disable
the events, and in that case there is no need to setup affinities as we
use a dummy CPU map, with just one entry set to -1.

So stop doing it to avoid this needless call to sched_getaffinity():

  # strace -ke sched_getaffinity perf stat -e cycles -p 241957 sleep 1
  <SNIP>
  sched_getaffinity(0, 512, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31]) = 8
   > /usr/lib64/libc-2.33.so(sched_getaffinity@@GLIBC_2.3.4+0x1a) [0xe6eea]
   > /var/home/acme/bin/perf(affinity__setup+0x6a) [0x532a2a]
   > /var/home/acme/bin/perf(__evlist__disable.constprop.0+0x27) [0x4b9827]
   > /var/home/acme/bin/perf(cmd_stat+0x29b5) [0x431725]
   > /var/home/acme/bin/perf(run_builtin+0x6a) [0x4a2cfa]
   > /var/home/acme/bin/perf(main+0x612) [0x40f8c2]
   > /usr/lib64/libc-2.33.so(__libc_start_main+0xd4) [0x27b74]
   > /var/home/acme/bin/perf(_start+0x2d) [0x40fadd]
  <SNIP>

Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20220117160931.1191712-5-acme@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2022-01-18 09:24:58 -03:00
arch virtio,vdpa,qemu_fw_cfg: features, cleanups, fixes 2022-01-18 10:05:48 +02:00
block SCSI misc on 20220113 2022-01-14 14:37:34 +01:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2022-01-17 05:49:30 +02:00
Documentation dmaengine updates for v5.17-rc1 2022-01-18 14:03:34 +02:00
drivers dmaengine updates for v5.17-rc1 2022-01-18 14:03:34 +02:00
fs virtio,vdpa,qemu_fw_cfg: features, cleanups, fixes 2022-01-18 10:05:48 +02:00
include dmaengine updates for v5.17-rc1 2022-01-18 14:03:34 +02:00
init Merge branch 'modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux 2022-01-17 07:32:51 +02:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-11-20 10:35:54 -08:00
kernel Merge branch 'modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux 2022-01-17 07:32:51 +02:00
lib Merge branch 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2022-01-17 05:49:30 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm slab changes for 5.17 - part 2 2022-01-18 06:40:47 +02:00
net virtio,vdpa,qemu_fw_cfg: features, cleanups, fixes 2022-01-18 10:05:48 +02:00
samples Tracing updates for 5.17: 2022-01-16 10:15:32 +02:00
scripts Merge branch 'for-5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/jlawall/linux 2022-01-17 08:00:56 +02:00
security fs.idmapped.v5.17 2022-01-11 14:26:55 -08:00
sound virtio,vdpa,qemu_fw_cfg: features, cleanups, fixes 2022-01-18 10:05:48 +02:00
tools perf evlist: No need to setup affinities when disabling events for pid targets 2022-01-18 09:24:58 -03:00
usr initramfs: Check timestamp to prevent broken cpio archive 2021-10-24 13:48:40 +09:00
virt RISCV: 2022-01-16 16:15:14 +02:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap RISCV: 2022-01-16 16:15:14 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Removing Ohad from remoteproc/rpmsg maintenance 2021-12-08 10:09:40 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS virtio,vdpa,qemu_fw_cfg: features, cleanups, fixes 2022-01-18 10:05:48 +02:00
Makefile - Get rid of all the .fixup sections because this generates 2022-01-12 16:31:19 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.